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National Aeronautics and Space Administration 14 Forcings on the Greenhouse

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National Aeronautics and Space Administration This figure depicts mostly positive and long- lived forcing agents from 1950 through The positive forcing agents are items that cause the atmosphere to show an overall warming trend because they trap additional energy in the atmosphere (enhanced greenhouse effect). The greenhouse gasses shown in the figure (carbon dioxide - CO 2, methane - CH 4, halocarbons, nitrous oxide - N 2 O and stratospheric + tropospheric ozone - O 3 ) have increased in the atmosphere mostly due to human activities. A natural change from variations in the Sun’s output is shown along the bottom of the graph This figure shows the cumulative effect of small changes. The additional heat trapped each year continues to add up to a warmer Earth. Physics of Our Atmosphere 15 Energy Balance analysis

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National Aeronautics and Space Administration Knowing how much additional heat is trapped (because we know how much of these gasses were emitted) the question becomes: where did the energy go? This figure partitions the added energy shown above based on observed changes. So far, a small amount of the energy has gone into warming the ocean – the part of the Earth that stores the most energy. Some has escaped Earth in the form of increased IR emission because of warmer temperatures. Some was reflected to space by aerosols (mostly volcanic in origin) in the stratosphere. The remainder (white band) is inferred to have been rejected due to aerosols (mostly pollution) in the troposphere, and other effects such as a changing reflection of the land surface due to deforestation, for example. Physics of Our Atmosphere 16 Where did the Energy Go?